4,152 research outputs found
Newly discovered halos and outer features around southern planetary nebulae
We have used the SuperCOSMOS H-alpha Survey to look for faint outer
structures such as halos, ansae and jets around known planetary nebulae across
4000 square degrees of the southern Milky Way. Our search will contribute to a
more accurate census of these features in the Galactic PN population. Candidate
common-envelope PNe have also been identified on the basis of their
microstructures. We also intend to determine more reliable distances for these
PNe, which should allow a much better statistical basis for the post-AGB total
mass budget. Our survey offers fresh scope to address this important issue.Comment: 2 pages, 1 figure. To be published in Planetary Nebulae: an Eye to
the Future, Proceedings of IAU Symposium 283, held in Puerto de la Cruz,
Tenerife, Spain, July 25-29 201
Interpreting the Atmospheric Neutrino Anomaly
We suggest that the atmospheric neutrino anomaly observed in the
Super-Kamiokande (and other) experiments results from the combined effects of
muon-neutrino to tau-neutrino oscillations with a Delta m^2 value of
approximately 0.4 eV^2 and oscillations between muon neutrinos and electron
neutrinos (and vice-versa) with 0.0001 < Delta m^2 < 0.001 eV^2. With an
appropriate choice of a three-neutrino mixing matrix, such a hypothesis is
consistent with essentially all neutrino observations.Comment: 12 pages, 2 eps figures, Latex2e, elsart style, submitted to Physics
Letters B --REV2-- Updated figure 1 and added figure 2: Super-K single R dat
Generalizing about trade show effectiveness: a cross-national comparison.
Trade shows are a multi-billion dollar business in the US and the UK, but little is known about the determinants of trade show effectiveness. In this paper, we build a model that explains differences in trade show effectiveness across industries, across companies and across two countries. We focus on the differences in trade show effectiveness measured in a similar way across similar samples of 171 US and 135 UK firm-show experiences between 1980 and 1991. While the similarities outweigh the differences, we find evidence that trade shows are viewed differently by exhibitors and attendees in these two countries. We are able to make substantial generalizations about the effect of various show selection (go-not go) variables (booth size, personnel, etc.) on observed performance. We discuss the implications of our research for developing benchmarks for trade show performance and for better global management of the business marketing communications mix.Effectiveness; Trade;
MSW mediated neutrino decay and the solar neutrino problem
We investigate the solar neutrino problem assuming simultaneous presence of
MSW transitions in the sun and neutrino decay on the way from sun to earth. We
do a global -analysis of the data on total rates in Cl, Ga and
Superkamiokande (SK) experiments and the SK day-night spectrum data and
determine the changes in the allowed region in the \dm - \tan^2\theta plane
in presence of decay. We also discuss the implications for unstable neutrinos
in the SNO experiment.Comment: Final version to appear in Phys. Rev.
Constraints on decay plus oscillation solutions of the solar neutrino problem
We examine the constraints on non-radiative decay of neutrinos from the
observations of solar neutrino experiments. The standard oscillation hypothesis
among three neutrinos solves the solar and atmospheric neutrino problems. Decay
of a massive neutrino mixed with the electron neutrino results in the depletion
of the solar neutrino flux. We introduce neutrino decay in the oscillation
hypothesis and demand that decay does not spoil the successful explanation of
solar and atmospheric observations. We obtain a lower bound on the ratio of the
lifetime over the mass of , (\tau_2/m_2) > 22.7 (\srm/\MeV) for the
MSW solution of the solar neutrino problem and (\tau_2/m_2) > 27.8
(\srm/\MeV) for the VO solution (at 99% C.L.).Comment: 8 pages latex file with 4 figure
A long trail behind the planetary nebula HFG1 (PK 136+05) and its precataclysmic binary central star V664 Cas
A deep wide-field image in the light of the Halpha+[N II] emission lines, of
the planetary nebula HFG1 which surrounds the precataclysmic binary system V664
Cas, has revealed a tail of emission at least 20' long, at a position angle of
316deg. Evidence is presented which suggests that this is an ~10^5 y old trail
of shocked material, left behind V664 Cas as it ejects matter whilst ploughing
through its local interstellar media at anywhere between 29 and 59 km/s
depending on its distance from the Sun.Comment: 3 pages, 1 figure, accepted for publication in MNRA
Neutrino Anomalies without Oscillations
I review explanations for the three neutrino anomalies (solar, atmospheric
and LSND) which go beyond the ``conventional'' neutrino oscillations induced by
mass-mixing. Several of these require non-zero neutrino masses as well.Comment: 14pages, LATEX format, 3 figure
Spectroscopic investigation of unstudied southern PNe
We present a spectroscopic investigation of two hitherto unstudied galactic
planetary nebulae (MeWe 1-10 and MeWe 1-11) and one candidate object (MeWe
2-5). The candidate object clearly has been identified as a bipolar hourglass
shaped PN. The galactic foreground extinction was derived and using
photoionization models with CLOUDY the two round objects were classified as
highly evolved nebulae.Comment: LaTeX, 5 pages with 6 figures, accepted in Astron. & Astrophy
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